NEPA--Environmental Assessment

Silverton Grazing Risk Assessment
Needles Mountains (FS, vacant allotment): There are no records of any permitted livestock
being grazed on this allotment. Very little suitable domestic sheep range exists in the
allotment due to generally steep and rugged mountainous terrain. In addition, there are
very limited access routes into the allotment. There is a large area of overlap with mapped
summer range, summer concentration, and winter range areas with the S71 West Needles
bighorn sheep herd. If this allotment were to be restocked with domestic sheep, potential
for contact with bighorn sheep appears to be high. Moving domestic sheep from another
allotment in the Landscape to the Needles Mountains Allotment would be moving sheep to
an area of equal or greater risk for contact with bighorn sheep. For this reason, we
recommend closing the Needles Allotment.
Fall Creek, Johnson Creek, Leviathan, Rock Creek, Cave Basin, and Flint Creek (FS,
vacant allotments): These six allotments are all outside the Silverton Landscape. Five of
the six allotments have not been grazed by domestic sheep since 1974. The Cave Basin
Allotment was last grazed by sheep in 1988. They were vacated largely due to their
location in remote areas of the Weminuche Wilderness with difficult access, and their
relatively small size for a sustainable season of grazing. All of these allotments would have
a high potential for contact with bighorn sheep, either by overlap with or close proximity
to mapped bighorn summer range of the S28 Vallecito Creek bighorn sheep herd, or by
overlap or close proximity with their associated stock driveways necessary for
ingress/egress of domestic sheep bands. There have been few requests from the domestic
sheep industry to use these remote areas. There is a slight possibility that if several of
these allotments were combined, a logical grazing unit could be developed and managed
effectively. However, the high potential for contact with the S28 bighorn herd would likely
remain and would be difficult to mitigate. Moving domestic sheep from the Silverton
Landscape to any one or combination of these six allotments would be moving sheep to an
area of equal or greater risk for contact with bighorn sheep. For these reasons we
recommend these seven allotments not be considered for restocking with domestic sheep
from active allotments in the Silverton Landscape.
Pine River Allotment (FS, vacant allotment): This is a large vacant allotment that includes
much of the headwaters of the Pine River in the central Weminuche Wilderness. This
allotment has been vacant since 1980. This allotment has been vacant largely due to its
remote location in the central Weminuche Wilderness and the requirement to trail
animals a long distance via the Pine-Piedra Stock Driveway. There is substantial summer
recreation in the Granite Lake, Snowslide Canyon, Rincon La Vaca, and Rincon La Osa
portions of this allotment, and the Continental Divide Trail parallels the boundary of this
allotment for a number of miles.
There is substantial overlap between the Pine River Allotment and mapped summer range
of the S16 Cimmarona/Hossick bighorn sheep herd, including all of Snowslide Canyon.
Mapped bighorn summer range for S16 extends from the headwaters of the Piedra River
drainage west to the Pine River at the mouth of Rincon La Osa, making domestic sheep
access to or from the Pine River very difficult without passing through mapped bighorn
sheep summer range. In addition, the Rincon La Osa portion of the Pine River Allotment
is within 1 to 2 air miles of mapped summer range of the S28 Vallecito Creek bighorn
sheep herd.
Historic livestock ingress/egress to the Pine River Allotment was from the south along the
Pine-Piedra Stock Driveway, or along the Pine River Trail from Vallecito Reservoir. Both of
these routes pass through the heart of the S28 Vallecito Creek bighorn sheep herd’s
summer range and summer concentration area. The Pine River Trail is an extremely
D-8